getting to the back molars

I have indeed been brushing chesters teeth, although not as often as I should . Problem is that no toothbrush that I've tried (I've tried the slip on finger ones, and a baby tiger toothbrush) can get between his cheek and his teeth to clean the back molars. I know from experience that's where tooth decay builds up the fastest. Can anyone think of a way for me to get back in there to brush??
Thanks a bunch!
Jess

I find that the CET cat toothbrush works best for this.

I didn't even know that the back molars were the prime candidates for tooth decay. Will pay extra attention from now on. I must admit that I do give the back molar less attention than they deserve.... so garsh darn hard to get to.

And Frodo would always give me this face when I try to awkwardly reach back there:

well, I think doing something is better than nothing, BUT. Over the last few years our whole crew has been seniors. ALL of them have suffered from tooth decay in the back. It makes sense, the saliva cant get between the cheek and tooth as easily, kinda trapping any gunk back in there. I'd rather not see my new kitten go through having teeth extracted if I can. YUCK!
Thanks Coster, I'll look for that brush.